Falmouth is a town in Barnstable County, Massachusetts, United States; Barnstable County is coextensive with Cape Cod. The population was 31,532 at the 2010 census,[2] making Falmouth the second-largest municipality on Cape Cod (behind only Barnstable). The terminal for the Steamship Authority ferries to Martha's Vineyard is located in the village of Woods Hole in Falmouth. Woods Hole also contains several scientific organizations such as the Woods Hole Oceanographic Institution, the Marine Biological Laboratory (MBL), the Woods Hole Research Center, National Marine Fisheries Aquarium, and the scientific institutions' various museums.

According to the United States Census Bureau, the town has a total area of 54.4 square miles (141.0 km2), of which 44.1 square miles (114.1 km2) is land and 10.3 square miles (26.8 km2), or 19.04%, is water.[2] Most of Falmouth, like the rest of Cape Cod, sits on glacial sands composed of glacial outwash deposits. However, the soil in the southwestern part of the town, consisting of moraine deposits, is more rocky and dense, like the rest of New England, and many glacial erratics are scattered about, dropped by the retreating glaciers. The climate is temperate marine. There is no exposed bedrock. Rainfall is evenly distributed throughout the year and averages 2 to 3 in (50 – 75 mm) per month.

Falmouth lies on the southwestern tip of Cape Cod. It is bordered by Bourne and Sandwich to the north, Mashpee to the east, Vineyard Sound to the south, and Buzzards Bay to the west. At its closest point, Falmouth is approximately 560 yards (510 m) from Nonamesset Island, the easternmost island of the town of Gosnold and the Elizabeth Islands. It is approximately 3 1⁄3 miles (5.4 km) north-northwest of Martha's Vineyard, the closest land to the island. Falmouth is approximately 14 miles (23 km) south of the Bourne Bridge, 22 miles (35 km) west of Barnstable, and 77 miles (124 km) south-southeast of Boston.

Falmouth's topography is similar to the rest of Cape Cod's, with many small ponds, creeks and inlets surrounded by the pines and oaks of the Cape and often rocky beachfront. Falmouth's southern shore is notable for a series of ponds and rivers spaced very closely together, all of which travel some distance into the town. These include, from west to east, Falmouth Inner Harbor, Little Pond, Great Pond (which leads to the Dexter and Coonamesset rivers), Green Pond, Bourne's Pond, Eel Pond (which leads to the Childs River), and Waquoit Bay, which lies along the Mashpee town line. The Buzzards Bay side of the town is primarily bays divided by necks, peninsulas connected to land by isthmi. The largest inlet is Megansett Cove along the Bourne town line. The Buzzards Bay shore of Falmouth is punctuated by a number of hamlets, including, from north to south, Megansett, New Silver Beach, Old Silver, Chappaquoit, Sippewisset, Quissett, and Woods Hole.